Motor operated valve with reduction gear
A small-sized motor operated valve is disclosed that has high output and high resolution by housing a reduction gear together with a rotor in a single can. A valve shaft 32 having a valve member 30 is inserted to a motor operated valve body 10 . A rotor 170 is disposed inside a can 100 attached to the body 10 , and inside the rotor 170 is housed a reduction gear 200 . The output of the rotor is input to a sun gear 220 and transmitted to planetary gears 230 . The planetary gears 230 are engaged both with the fixed gear 250 and the output gear 260 , and the output gear 260 is driven at reduced speed by a large reduction ratio. The output of the output gear 260 is transmitted via a driver 300 to a screw shaft 320 , where it is converted into a linear movement and transmitted to the valve shaft 32.
1. A motor operated valve with a reduction gear comprising:
a valve body having a valve chamber and a valve seat;
a valve member disposed in the valve chamber and movable on a longitudinal axis to open and close an opening of the valve seat;
a valve shaft for operating the valve member;
a cylindrical can fixed to the valve body and defining therewith an enclosed space centered on said axis;
a motor exciter comprising a stationary stator coil mounted on an outer circumference portion of the can and centered about said axis;
a permanent magnet rotor rotatably supported at an inner circumference portion of the can and driven to rotate by the exciter;
a reduction gear for reducing the rotation of the rotor; and
a screw mechanism for moving the valve member toward and away from the valve seat via the reduction gear by the rotary movement of the rotor, and
the reduction gear and the rotor being disposed together in said enclosed space and being centered on and rotatable about said axis to form a compact coaxial motor operated valve with gear reduction.
2. The motor operated valve according to claim 1 , wherein the reduction gear is disposed inside the rotor.
3. The motor operated valve according to claim 1 , wherein the reduction gear is disposed under the rotor.
4. The motor operated valve according to claim 1 , wherein the reduction gear includes a planetary gear mechanism.
5. The motor operated valve according to claim 1 , wherein the reduction gear is composed of a multistage train of gears.
6. The motor operated valve according to claim 1 , wherein the valve chamber includes a bellows sealing a gap between the valve shaft and the valve body.